Music can go silent for any number of basic reasons.
First if you are not using earbuds, crank up the volume. Volume gets turned down to zero for all sorts of reasons.
Second if you are wearing earbuds, make sure they are pushed all the way in and of course check the volume.
Earbuds wear out much faster than phones.
Also if you have another app that makes noise or downloaded music or even a reboot, try those and see if you get sound.
And of course try your ringtones. They are nice and noisy. This will tell you if you have a sour app, bad earbuds, or a corrupted file.